Waste packing system and film

ABSTRACT

The present invention is directed to a waste packaging system, a method of storing waste and to a film for use in this system and method.

The present U.S. patent application is a divisional application of U.S.patent application Ser. No. 13/157,876, filed Jun. 10, 2011, whichclaims priority to European Patent Application No. 11 164 527.1, filedMay 3, 2011, and European Patent Application No. 11 166 232.6, filed May16, 2011. The disclosure of each of these applications is incorporatedherein by reference in its entirety.

The present invention is directed to a waste packaging system, a methodof storing waste and to a film for use in this system and method.

A lot of waste products produce smells that are annoying to theenvironment. Examples are decayed food, kid nappies and cat litter.

In the prior art there are many films that could be used for protectionfrom malodors. As it is well known in the art, the use of materials likeEVOH, PVDC, polyacrylonitrile is recommended in order to not allowmalodors escape from the container (eg bag or other configuration) andcreate an unpleasant atmosphere.

There are also a lot of known configurations of packing a certain lengthof film (eg 20 meters) in a compressed form (eg in a cassette). Examplesof the representative cassettes are shown in U.S. Pat. No. 4,934,529 orU.S. Pat. No. 3,536,192.

Generally the cassette comprises a tubular core, casing wall, cassettebottom and lid. The film is stored in an area between tubular core,casing wall and cassette bottom in a compressed configuration. Theflexible tubing is dispensed from the cassette. After the malodorousitem is thrown into the bag the core or the lid is rotated and theflexible tube is twisted so that it closes as hermetically as possiblethe waste/environment area. To dispose the next diaper the user opensthe lid and inserts the diaper. The previous pack is pushed downward anda new knot is formed by twisting the tube above the newly depositeddiaper. Thus the device stores the diapers in a series of individuallywrapped packages in the storage chamber, each package being separatedfrom adjacent packages by twists in the tube.

Separation of one piece of flexible film from the next by means of arotary knife is preferred.

In the prior art as a general rule the separation of each piece of thefilm in which the smelly item is contained from the next piece of thefilm is done with a twisting mechanism. This twist separates in a“hermetic” way the one piece from the other.

That is to say, it is a problem in the prior art techniques that thetwist is never really hermetic. Odour molecules being extremely smallhave the capability to escape through the folds so the odour starts tobe noticeable after a few days. There is still a need for a morehermetic way to isolate each individual pack with the next one.

Methods based on heat sealing have been proposed in the prior art as forexample in EP 0005660. This concept is quite complicated as it usessheaths to form discrete packages. The complex nature of this designmakes it expensive to manufacture.

According to the prior art document U.S. Pat. No. 4,869,049, the use ofelectricity is to be avoided anywhere near babies therefore thisapproach has not been commercially successful. So, twisting is thepreferred option for separating one pack from the next.

Heat sealing and cutting as means to separate each pack from the next isalso an object of U.S. Pat. No. 6,516,588. In this reference there is nomention to the use of a low voltage battery. So, in general this methodis not suitable enough as it involves electricity of high voltage andthis is to be avoided for this sensitive application. Also, there is noreference to a low voltage battery.

Further, U.S. Pat. No. 6,516,588 does not refer to a suitable film thatcan be sealed efficiently and also through pleats and wrinkles (whichare unavoidable during this kind of application).

According to this application “the plastic tubing may be any plastictubing known in the art” as described in col. 4 lines 30-31.

Further, U.S. Pat. No. 4,612,221 refers to a thin film incorporatingoxygen barrier material. The film comprises a cling agent (additivewhich offers cling property) and is suitable to be used as a food wrap.There is no mention of the possibility of the film to be used in a wastepacking system. Also the cling additive makes it unsuitable in a wastepacking system due to a number of reasons such as difficult unwinding,waxy feeling, more complicated production process etc.

The present invention provides a safe and simple apparatus that is quickand easy to operate, that stores soiled nappies in flexible tubing in avery hygienic way so that they can be disposed collectively after acertain amount of time. It also provides a suitable plastic film to beused accordingly.

SUMMARY OF THE INVENTION

The present invention in one aspect is directed to a device comprising

-   -   1. a dispensing apparatus wherein a plastic film with        weight/surface ration less than 20 grams per square meter is        stored    -   2. a bin wherein a fusion seal apparatus is located    -   3. a fusion seal apparatus comprising a battery with a maximum        voltage of 20V.

The battery may be rechargeable or non-rechargeable. Preferably, it isrechargeable.

Also another object of the present invention is a method of packingwaste items by

-   -   1. pulling out plastic film of weight/surface ration less than        20 grams per square meter from a dispensing apparatus    -   2. putting a waste item in a suitable length of the film    -   3. closing hermetically the plastic film with the use of a        fusion seal where the seal is between a part of the film and        another part of the same or other film, where the sealed parts        are put sequentially in a bin.

The fusion seal is preferably done with a fusion seal apparatuscomprising a battery with a maximum voltage of 20V.

Also another object of the present invention is a plastic filmcomprising at least a layer comprising at least 50% per weight ofpolyethylene homopolymer and/or copolymer, where the weight/surfaceratio is less than 20 grams per square meter and the film can be heatsealed with the thermal energy transferred with a battery with a voltageof less than 20 V.

In a preferred embodiment, the present invention provides a multilayerplastic film comprising at least

-   -   1. an outer layer comprising of polyethylene homopolymer and/or        copolymer    -   2. an internal layer comprising at least one oxygen barrier        material    -   3. an inner layer comprising polyethylene homopolymer and/or        copolymer,        where the weight/surface ratio is less than 20 grams per square        meter and the film can be heat sealed with the thermal energy        transferred with a battery with a voltage of less than 20 V.

In a preferred embodiment, the outer and/or inner layer comprise atleast 50% per weight of polyethylene homopolymer and/or copolymer.

The film preferably does not contain any cling agents.

Definitions

In this application the following definitions are used:

The term “waste” refers to any receptable that is useless and has to bedisposed of properly. For example, the term waste includes diapers orother dirt.

The term “dispensing apparatus” refers to any apparatus where the filmis stored before the application process. Examples are cassettes orreels.

The term “cassette” refers to any container wherein the film can be put.Often the film is in compressed form. The cassette is usually plasticand circular but other configurations may be possible.

The term “fusion seal” refers to the sealing of film by melting. Adifferent kind of seal is by twisting the plastic film or by used anadhesive (in this latter case a kind of seal is made by pressure alone).

The term “bin” refers to a container where many waste packs are put oneafter the other. Each pack comprises a portion of the sealed film and ofcourse the waste inside.

The term “film” refers to a flat or tubular flexible structure ofthermoplastic material.

The term “voltage” between two points refers to the electrical drivingforce that could determine an electric current between these points.

The term “battery” refers to one or more electrochemical cells thatconvert stored chemical energy to electrical energy.

The term “rechargeable” refers to batteries that are designed in a wayto be recharged and used multiple times.

The term “heat shrinkable” refers to a film that shrinks at least 10% inat least one of the longitudinal and transverse directions when heatedat 90° C. for 4 seconds. The shrinkability is measured in wateraccording to ASTM 2732. For temperatures like 100° C. or more, glycerineis used as a reference liquid.

The term “total heat shrinkability” refers to the sum of heatshrinkability at the MD direction and heat shrinkability at the TDdirection. In all cases, ASTM 2732 is used for measurement ofshrinkabilities.

The term “multilayer” refers to a film comprising 2 or more layers.

The phrase “longitudinal direction” or “machine direction” hereinabbreviated “MD” refers to a direction along the length of the film.

The phrase “outer layer” refers to the film layer which comes inimmediate contact with the outside environment (atmosphere).

The phrase “internal layer” as used herein refers to a film layerlocated between the outer and the inner layer of the multilayer film. Itis not in contact with the atmosphere or the good to be packaged andusually comprises an oxygen barrier material.

The phrase “inner layer” refers to the film layer that comes in directcontact with the product packed. This is also called “sealing layer” asthis layer must be hermetically sealed in order to protect the productfrom ingress of air.

The phrase “abuse layer” refers to a film layer whose main contributionto the film structure is to increase the abuse resistance property. Thelayer comprises materials which offer high impact strength to the film.Often, the abuse layer is an inner layer of the film, but it can formthe outer layer as well. In some embodiments, it may form an internallayer as well.

The phrase “intermediate layer” refers to a film layer whose maincontribution to the film structure is to increase the bonding between anoxygen barrier layer and another layer (eg abuse layer, inner layer,outer layer etc).

As used herein, the term “homopolymer” refers to a polymer resultingfrom polymerization of a single monomer.

As used herein, the term “copolymer” refers to a polymer resulting frompolymerization of at least two different polymers.

As used herein, the term “polymer” includes both above types.

As used herein, the term “polyolefin” refers to any polymerized olefin,which can be linear, branched, cyclic, aliphatic, substituted orunsubstituted. More specifically, included in the term polyolefin arehomopolymers of olefin, copolymers of olefin, copolymers of an olefinand a non olefinic comonomer (such as ester) etc.

Specific examples include polyethylene homopolymer, polypropylenehomopolymer, polybutene homopolymer, ethylene alpha olefin copolymer,propylene alpha olefin copolymer, butene alpha olefin copolymer,ionomer, ethylene ester copolymer etc.

As used herein the term “polyethylene” identifies polymers consistingessentially of the ethylene repeating unit. The ones that have a densitymore than 0.940 are called high density polyethylene (HDPE), the onesthat are have less than 0.940 are low density polyethylene (LDPE).

As used herein the phrase “ethylene alpha olefin copolymer” refers topolymers like linear low density polyethylene (LLDPE), medium densitypolyethylene (MDPE), very low density polyethylene (VLDPE), ultra lowdensity polyethylene (ULDPE), metallocene catalysed polymers andpolyethylene plastomers and elastomers.

As used herein the term “homogeneous ethylene alpha olefin copolymers”refer to ethylene alpha olefin copolymers having a molecular weightdistribution less than 2.7 as measured by GPC. Typical examples of thesepolymers are AFFINITY from DOW or Exact from Exxon.

As used herein the phrase “styrene polymers” refers to styrenehomopolymer such as polystyrene and to styrene copolymers such asstyrene-butadiene copolymers, styrene-butadiene-styrene copolymers,styrene-isoprene-styrene copolymers, styrene-ethylene-butadiene-styrenecopolymers, ethylene-styrene copolymers and the like.

As used herein the phrase “ethylene methacrylate copolymers” refers tocopolymers of ethylene and methacrylate monomer. The monomer content isless than 40%.

As used herein the phrase “ethylene vinyl acetate copolymer” or EVArefer to copolymers of ethylene and vinyl acetate.

As used herein the phrase “ethylene ester copolymer” includes anypolymer made from ethylene and ester monomers. It is obvious that thisterm includes EVAs, EMAs and other polymers.

As used herein the term “oxygen barrier polymer” refers to polymerswhich have the property to limit the passage of oxygen through a film ora layer comprising the polymer. Common materials, are EVOH, PVDC orpolyamide. Those polymers usually are comprised in at least one internallayer of the multilayer film.

As used herein, the term EVOH refers to saponified products of ethylenevinyl ester copolymers. The ethylene content is typically in the rangeof 25 to 50% per mol. All the later references to EVOH ethylene contentwill be in % per mol.

As used herein the term PVDC refers to a vinylidene chloride copolymerwherein a major amount of the copolymer comprises vinylidene chlorideand a minor amount of the copolymer comprises one or more monomers suchas vinyl chloride and/or alkyl acrylates and methacrylates.

As used herein the term “polyamide” refers to homopolymers andcopolymers. Polyamide 6, polyamide 66, polyamide 12, polyamide 6/66,polyamide 6/12, polyamide elastomers, MXD polyamides and othercopolymers are specifically useful for the invention.

As used herein the term “polyester” refers to polymers comprisingterephthalate units. Examples of polyesters are PET (polyethyleneterephthalate), PBT (polybutylene terephthalate), polyester elastomer(block copolymer comprising ester or ether units), PTT and other similarpolymers.

As used herein, the term “ionomer” comprises the copolymers of ethyleneand methacrylic or acrylic acid being metal neutralized. An example ofsuch material is Surlyn from Dupont.

As used herein, the term “polypropylene” refers to polymersincorporating propylene structural units. Examples of these, are homopolypropylenes, random copolymers of propylene and ethylene, blockcopolymers of propylene and ethylene, copolymers or blends of propyleneand rubber (such as blends of polypropylene and ethylene propylenerubber), propylene ethylene alpha olefin terpolymers and others.

These polymers may be isotactic, syndiotactic or atactic. Isotactic ispreferred.

In line with the above definition, it is noted that for the purposes ofthe present invention, the term “inner layer” is to be regarded as anadditional outer layer of the multilayer film, which is in directcontact with the item to be packaged (i.e. an outer layer of the filmwhich is located on the inside after a packaging process, not exposed tothe environment).

As used herein the term “substantially non resilient material” refers tomaterials or material compounds comprising at least 40% per weightinorganics like calcium carbonate, titanium dioxide, wollastonite, mica,glass fibers, dolomite and the like. The rest percentage per weight canbe polyethylene, polypropylene, styrene polymer or other thermoplasticmaterial.

All measurement methods mentioned herein are readily available for theskilled person. For example, they can be obtained from the AmericanNational Standards Institute at: www.webstore.ansi.org

All percentages are based on weight per weight ratio, except whenotherwise stated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of a presently disclosedapparatus.

FIG. 2 is a perspective view of an embodiment of a presently disclosedapparatus.

FIG. 3 is a side view of an embodiment of a presently disclosedapparatus.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a device comprising

-   -   1. a dispensing apparatus where a plastic film of weight/surface        ration less than 20 grams per square meter is stored    -   2. a bin where a fusion seal apparatus is located    -   3. a fusion seal apparatus comprising a battery with a maximum        voltage of 20V.

The battery preferably is rechargeable.

In some embodiments, the dispensing apparatus has the form of acassette.

In some embodiments, the voltage is less than 16 V. In some embodiments,the voltage is less than 12 V.

In some embodiments, the temperature for a heat seal is set to less than100° C., less than 90° C., or less than 80° C. In some embodiments, thesealing time is set to less than 5 seconds, less than 3 seconds, or lessthan 1 second.

Another aspect of the present invention is a method of packing wasteitems by

-   -   1. pulling out plastic film of weight/surface ration less than        20 grams per square meter from a dispensing apparatus    -   2. putting a waste item in a suitable length of the film    -   3. closing hermetically the plastic film with the use of a        fusion seal where the seal is between a part of the film and        another part of the same or other film, where the sealed parts        are put sequentially in a bin.

The fusion seal is preferably done with a fusion seal apparatuscomprising a battery with a maximum voltage of 20V.

A still further aspect of the present invention is a method of packingwaste items by

-   -   1. pulling out plastic film of weight/surface ration less than        20 grams per square meter from a dispensing apparatus    -   2. putting a waste item in a suitable length of the film    -   3. closing hermetically the plastic film with the use of a        fusion seal where the seal is between a part of the film and        another part of the same or other film where the film is able to        be sealed through pleats and wrinkles,        -   where the sealed parts are put sequentially in a bin.

A preferred embodiment of the present invention is a method of packingwaste items by

-   -   1. pulling out plastic film of weight/surface ration less than        15 grams per square meter from a dispensing apparatus    -   2. putting a waste item in a suitable length of the film    -   3. closing hermetically the plastic film with the use of a        fusion seal where the seal is between a part of the film and        another part of the same or other film where the film is able to        be sealed through pleats and wrinkles,        where the sealed parts are put sequentially in a bin.

Also another object of the present invention is a plastic filmcomprising at least a layer comprising at least 50% per weight ofpolyethylene homopolymer or copolymer, where the weight/surface ratio isless than 20 grams per square meter and the film can be heat sealed withthe thermal energy transferred with a battery with a voltage of lessthan 20 V.

Also another object of the present invention is a multilayer plasticfilm comprising at least

-   -   1. an outer layer comprising polyethylene homopolymer and/or        copolymer    -   2. an internal layer comprising at least one oxygen barrier        material    -   3. an inner layer comprising polyethylene homopolymer and/or        copolymer,        where the weight/surface ratio is less than 20 grams per square        meter and the film can be heat sealed with the thermal energy        transferred with a battery with a voltage of less than 20 V.

In a preferred embodiment, one or both of the outer and inner layerscomprise at least 50% per weight of polyethylene homopolymer and/orcopolymer.

Dispensing Apparatus

A dispensing apparatus of the present invention preferably has the formof a cassette. Nevertheless, other dispensing apparatus are alsopossible in which a cassette is not used. For example the film can bewound in the form of a mini roll around a paper core. Alternatively, twosuch mini rolls may comprise the film in such a way that the film woundin the first mini roll will heat seal to the film that is wound in thesecond mini roll.

Cassette

In a preferred embodiment the cassette useful for the invention iscircular in shape (see FIG. 1). Preferably it is made by plastic, egpolypropylene.

It is also possible to be manufactured from other means more friendly tothe environment such as paper, biodegradable plastic or nonbiodegradable plastic where a percentage of “degrading” additives havebeen added.

Generally, the cassette comprises a tubular core (see reference number14 in FIG. 1), casing wall (see reference number 12 in FIG. 1), cassettebottom and lid (see reference number 13 in FIG. 1). The film is storedin an area between tubular core, casing wall and cassette bottom in acompressed configuration. The flexible tubing is dispensed from thecassette.

In a further preferred embodiment of the invention the cassettecomprises a malodor counteractant useful for absorbing, adsorbing ormasking the smell of the waste.

In a preferred embodiment of the invention the film inside the cassettethe film is in compressed configuration.

Seal Apparatus

A preferred version of the sealing apparatus of the present invention isan apparatus capable of impulse sealing. An impulse sealer is a jawsealer backed with resilient silicone rubber. Electric current flowsthrough Nichrome ribbon stretched over one over one or both surfaces andcovered with high temperature release film and fabric.

Another preferred version of the seal apparatus is wire or knifesealing. According to this method a hot wire or knife seals and cuts thefilm.

Other methods for the seal apparatus that could be used according to theinvention include bar sealing, band sealing, ultrasonic sealing,friction sealing, gas sealing, contact sealing, hot melt sealing,pneumatic sealing, dielectric sealing, magnetic sealing, inductionsealing, radiant sealing, solvent sealing etc. For these methods pleaserefer to the Wiley Encyclopedia of packaging technology, edition 1997.

In a preferred embodiment of the invention the electric currentnecessary for the heat sealing and fusion is provided through arechargeable battery. The voltage of the rechargeable battery ispreferably equal or less than 20 V, even more preferably less than 16 V,even more preferably less than 12V.

In a preferred version of the invention the temperature for the heatseal is less than 100° C., preferably less than 90° C., preferably lessthan 80° C.

In a further preferred version of the invention, the sealing time isless than 5 seconds, more preferably less than 3 seconds, morepreferably less than 1 second.

In a further preferred version of the invention, the cutting of eachpack to the previous one is done simultaneously with the sealing by theuse of a wire/knife configuration. In another version, there is nocutting. In this case all the packs are put together inside the bin in asingle line.

The use of a rechargeable battery of low voltage assures a safeprocedure that is more user friendly than household electricity.

Another alternative possibility of the invention is the use of more thanone heat seal to make an individual pack. So two, three or four sealsare possible.

In the case of three or four seals, the film should be in a “singlesheet” configuration instead of “flexible tubing”.

In FIG. 2 there is further explanation of the sealing apparatus. The twosealing jaws (see reference number 23) are heat sealing the flexibletubular film. The sealing jaws are movable on a railway (see referencenumber 22) and the movement is controlled through as gear reducer (seereference number 21). This is also displayed in FIG. 3 from anotherview.

The activation of the sealing mechanism can be done by the person usingthe apparatus preferably by pushing an activation mechanism (eg a buttonor a lever) either by hand or by foot. The activation mechanism provokesby preferably mechanical or pneumatic transmission system the movementof the sealing jaws therefore allowing the fusion seal to occur.Electrical transmission is also possible by using a battery as a sourceof power.

Film Characteristics

The basic characteristics a film should have in order to be used in theparticular case are

-   -   1. Barrier to odours    -   2. To have the proper deadfold properties (non resilient) so        that is compressed efficiently in the cassette if a cassette is        used as a dispensing apparatus.    -   3. To have sufficient mechanical properties (eg tensile strength        at break, elongation).    -   4. To have sufficient sealing properties as to be sealed with a        low voltage rechargeable battery. Also the sealing properties        must be sufficient to seal through wrinkles or pleats that are        inevitable for this kind of application.

We have surprisingly found that all these features can be achieved witha very lightweight multilayer film with weight per surface ratio lessthan 20 grams per square meter, preferably less than 18 grams per squaremeter. This is extremely beneficial for the environment as multilayerfilms are extremely difficult to be produced with so small weight persurface.

In order for a film to be able to heat seal hermetically to itself or toother film with the power generated by a low voltage battery and also beable to keep the other critical characteristics (odour barrier,sealability through pleats and wrinkles, mechanical strength) it shouldcombine the following characteristics:

-   -   1. Comprise an internal layer comprising at least one oxygen        barrier material    -   2. Comprise one outer layer comprising more than 50% per weight        polyethylene homopolymer and/or copolymer and one inner layer        comprising more than 50% per weight polyethylene homopolymer        and/or copolymer    -   3. Have a weight/surface ratio of less than 20 grams per square        meter.    -   4. The film can be heat sealed with the thermal energy        transferred with a battery with a voltage of equal or less than        20 V.

According to a further aspect the present invention is directed to amultilayer film with weight less than 15 g/m² which:

-   -   1. Comprises a layer comprising at least one oxygen barrier        material    -   2. Comprise one outer layer comprising more than 50% per weight        polyethylene homopolymer and/or copolymer and one inner layer        comprising more than 50% per weight polyethylene homopolymer or        copolymer    -   3. The film can be heat sealed with the thermal energy        transferred with a battery with a voltage of equal or less than        20 V.

According to a further aspect the present invention is directed to amultilayer film with weight less than 13 g/m² which:

-   -   1. comprises a high oxygen barrier layer comprising at least one        oxygen barrier material    -   2. comprise two outer layers comprising more than 50% per weight        polyethylene homopolymer or copolymer    -   3. the film can be heat sealed with the thermal energy        transferred with a battery with a voltage of equal or less than        20 V.

In a further preferred embodiment, the film comprises the construction:

Outer Layer/Abuse Layer/Intermediate Layer/Barrier Layer/IntermediateLayer/Abuse Layer/Inner Layer

In another preferred embodiment, the film comprises the construction

Outer Layer/Intermediate Layer/Barrier Layer/Intermediate Layer/InnerLayer

Detailed Description of Layers:

Barrier (Internal) Layer

In a preferred version of the invention, the oxygen barrier material inthe barrier (internal) layer is EVOH, PVDC or polyamide. The EVOH usedpreferably has an ethylene content less than 48%, more preferably lessthan 44%, more preferably less than 38%, more preferably from 27 to 32%ethylene.

The oxygen barrier material preferably has a weight of less than 3 g/m²,more preferably less than 2 g/m² and even more preferably less than 1.5g/m².

Outer Layer

In a preferred version, the outer layer comprises at least 50% perweight polyethylene homopolymer or copolymer.

In a further preferred version, the weight of the outer layer is lessthan 6 g/m², more preferably less than 5 g/m².

In a further preferred version, the polyethylene is a copolymer or ablend of different monomers or polymeric structures. This blending maytake place during polymerization or as a later stage.

In a further preferred version the polyethylene is a copolymer ofethylene and butene or a copolymer of ethylene and hexene or a copolymerof ethylene and octene.

In a further preferred version the polyethylene has a density of between0.885 and 0.960 g/m³, more preferably 0.910 to 0.940 g/m³.

Inner Layer

Preferred materials for the inner layer include polyethylene homopolymeror copolymers, such as low density polyethylene, high densitypolyethylene, ethylene ester copolymer, ethylene alpha olefin copolymerand ethylene propylene copolymers. Ethylene based ionomers and ethylenestyrene copolymers are also possible. Ethylene alpha olefin copolymer isparticularly preferred.

According to a further embodiment, the present invention is of the sameconfiguration where the inner layer comprises a “substantially nonresilient material” (SNR).

In a preferred version of the invention, the SNR material is at least 10percent, preferably at least 20, preferably at least 30 percent perweight of the inner layer.

Intermediate Layer

In the intermediate layers, typical adhesive resins like maleicanhydrite modified polyolefins may be used. Typical examples are BYNELfrom Dupont and OREVAC from Arkema.

In another preferred version of the invention, polyamide could be usedas intermediate layer.

Abuse Layer

In a multilayer configuration where abuse layers are also present, theselayers may comprise polyethylene and polypropylene homopolymers orcopolymers. Polyamides are also possible.

General

Additives well known in the art may be used in one or more layers of thepresent invention. Slip additives, antiblock additives, antifog, polymerprocessing aids may be used if pertinent. Antimicrobial additives mayalso be used in one or more of the layers to inhibit the microbeformation. Preferably the antimicrobial is put on the side where thewaste is in direct vicinity.

In order to increase the mechanical properties the film may becrosslinked with one of the following methods.

E-beam radiation, gamma radiation, moisture crosslinking using silanegrafting compounds, peroxide crosslinking.

The film may be in tubular form or sealed at the edges or single sheetconfiguration. Centrefold configuration is also possible.

The preferred production method for the film is the hot blown filmmethod, which is well known in the art. Other methods like extrusionthrough flat cast die is also possible. The hot blown film method allowsorientation of the plastic from the melt state. Biaxiallly oriented filmsuch as those produced by double bubble or tenter frame method are notreally efficient for the application during the much higher complexityof the process which renders the production cost much higher.

As outlined above, the inner and outer layers of the present inventionare substantially free of “cling” additives meaning additives that allowthe layer adhere to itself by pressing force without the need of fusionseal. Addition of such additives is costly and complicated. Also itmakes the whole process much less friendly due to the tacky nature ofthe cling additive.

EXAMPLES

A 5 layer film is produced in a commercial hot blown film line with thefollowing recipe

Inner layer, 80% EAO1+15% SNR1+5% ADDITIVES

Adjacent layer 100% ADH 1

Barrier layer EVOH 1

Adjacent layer 100% ADH1

Outer layer 100% EAO1

See table 1

The thickness of the structure is 4/1.5/1.5/1.5/4 starting from theinner and going to the outer layer. The weight of the film is 12.145g/m².

TABLE 1 Density Type Description g/cm³ EAO1 Ethylene octene 0.92copolymer SNR1 Calcium 1.6 carbonate compound AD1 LLDPE mod. 0.92Adhesive tie EVOH 1 EVOH with 32% 1.19 ethylene EVOH 2 EVOH with 29% 1.2ethylene

Example 2

A 5 layer film is produced in a hot blown film commercial line with thefollowing recipe

Inner layer, 80% EAO1+15% SNR1+5% ADDITIVES

Adjacent layer 100% ADH 1

Barrier layer EVOH 2

Adjacent layer 100% ADH1

Outer layer 80% EAO1+15% SNR1+5% ADDITIVES

The thickness of the structure is 5/1.5/1.5/1.5/3 starting from theinner and going to the outer layer.

The weight of the material is 12.385 g/m².

Example 3

A 5 layer film is produced in a hot blown film commercial line with thefollowing recipe

Inner layer, 80% EAO1+15% SNR1+5% ADDITIVES

Adjacent layer 100% ADH 1

Barrier layer EVOH 2

Adjacent layer 100% ADH1

Outer layer 80% EAO1+15% SNR1+5% ADDITIVES

The thickness of the structure is 5/3/1.5/3/5 starting from the innerand going to the outer.

The weight of the material is 17.1 g/m².

Tests

-   -   1. Tensile strength and elongation test is done according to        ASTM D 882.    -   2. Odour test is done in the way described below.        Test 1.

Tensile strength and elongation is measured as per ASTM D882.

MD stands for machine direction, whereas TD stands for transversedirection.

TENSILE ELONGA- TENSILE ELONGA- STRENGTH TION STRENGTH TION EXAMPLE (MD)(MD) (TD) (TD) 1 22 250 21 630 2 21 225 19.8 550 3 25 190 23 520Odour Testing

10 soiled diapers are put in a film of the present invention and also ina commercially sold film. The commercially sold film is believed to bemonolayer.

The packs are put in PVDC comprising bags, so the odour cannot escapeduring the time of the evaluation.

The bags are opened 3 days after the soiling of the diapers and smellwas evaluated by a 5 member panel.

The packs made from examples 1 and 2 were found substantially lesssmelly than the commercially sold ones.

Sealing Testing

The sealing testing was done in comparison with a commercial filmspecialized for the particular application with a weight/surface ratioof 21.9 g/m². For the testing two sealing jaws that used the energyproduced by a battery of 20 V were used.

It was surprisingly found that the film of examples 1, 2 and 3 were ableto seal efficiently even through wrinkles with the sealing apparatus. Onthe other hand, the film of 21.9 g/m² was not able to seal efficiently.If the sealing time was increased (something which is not desirableaccording to the invention) the seal was “burned”.

What is claimed is:
 1. A method for storing waste by using a devicecomprising (i) a dispensing apparatus where a plastic film ofweight/surface ratio less than 20 grams per square meter is stored; (ii)a fusion seal apparatus comprising a battery with a maximum voltage ofequal to or less than 20 V; and (iii) a bin where the fusion sealapparatus is located; the method comprising: a. pulling out the plasticfilm of weight/surface ratio less than 20 grams per square meter fromthe dispensing apparatus; b. putting a waste item in a suitable lengthof the plastic film; and c. closing hermetically the plastic film withthe use of the fusion seal apparatus to provide a seal between a part ofthe plastic film and another part of the same plastic film, where thesealed parts are put sequentially in the bin.
 2. A plastic film for usein the method according to claim 1, comprising at least an outer layercomprising at least 50% per weight polyethylene homopolymer and/orcopolymer, where the weight/surface ratio of the plastic film is lessthan 20 grams per square meter and where the plastic film can be heatsealed with the thermal energy transferred with the battery with thevoltage of equal to or less than 20 V.
 3. The plastic film of claim 2,further comprising an internal layer comprising at least one oxygenbarrier material and/or a sealing layer comprising at least 50% perweight polyethylene homopolymer and/or copolymer, wherein the sealinglayer is a layer configured to be sealed using the fusion sealapparatus, and wherein the internal layer is a film layer locatedbetween other layers of the plastic film.
 4. The plastic film of claim2, comprising a sealing layer comprising at least 50% per weightpolyethylene homopolymer and/or copolymer.
 5. The plastic film of claim2, where the weight/surface ratio is less than 15 g/m².
 6. The plasticfilm of claim 2, where the weight/surface ratio is less than 13 g/m². 7.The plastic film of claim 2, comprising an internal layer comprising anoxygen barrier material, where the oxygen barrier material is EVOH, PVDCor polyamide.
 8. The plastic film of claim 2, where the polyethylenecopolymer is selected from the group consisting of a copolymer ofethylene and butene, a copolymer of ethylene and hexene, and a copolymerof ethylene and octene.
 9. A plastic film for use in the methodaccording to claim 1 comprising at least an outer layer comprisingpolyethylene homopolymer and/or copolymer; a sealing layer comprisingpolyethylene homopolymer and/or copolymer; and an internal layer locatedbetween the outer layer and the sealing layer, wherein said internallayer comprises at least one oxygen barrier material; where theweight/surface ratio of the plastic film is less than 20 grams persquare meter and where the plastic film can be heat sealed with thethermal energy transferred with the battery with the voltage of equal toor less than 20 V.
 10. The plastic film of claim 9, wherein the outerand/or sealing layer comprise at least 50% per weight polyethylenehomopolymer and/or copolymer.
 11. The plastic film of claim 9, where theweight/surface ratio is less than 15 g/m².
 12. The plastic film of claim9, where the weight/surface ratio is less than 13 g/m².
 13. The plasticfilm of claim 9, where the oxygen barrier material is EVOH, PVDC orpolyamide.
 14. The plastic film of claim 9, where the polyethylenecopolymer is selected from the group consisting of a copolymer ofethylene and butene, a copolymer of ethylene and hexene, and a copolymerof ethylene and octene.